Effect of Density, Moisture and Geometry on the Normalize Burn Rate of Low Pressure Biomass Briquettes

In this study, the variation of steady-state combustion rate (otherwise called Normalized Burn Rate, NBR) with the density, moisture content and geometry of saw dust, palm fibre and rice husk briquettes, burned in free air was investigated. The quest for alternative fuel for heating and cooking as a result of depletion of fossil fuel and environmental pollution associated with it burning has necessitated the need to improve on the use of loose agro-waste as alternative. Cylindrical briquettes were used through out the experiment except for the effect of geometry where cylindrical briquettes with central hole and cylindrical solid briquettes were used. The briquettes were formed by compression of the pulp in the mould with an Instron compression test machine at a pressure range between 1.5 and 7.5Nmm2 which formed briquettes with densities between 200 and 500kgm-3. The results show that the NBR for the three briquette samples: wood saw dust, palm fibre and rice husk respevtively, were found to decrease as the density and moisture content increases. It was observed that hollow briquette had a higher NBR than solid briquette of the same pressure and relaxed diameter with saw dust having the highest variation and rice husk the least. The results show that briquettes could be a viable alternative to wood fuel.